Technitribe

For me, the holy grail of working with virtual machines is

$ ssh root@my-vm

I am tired of manually updating /etc/hosts or looking at arp tables¹. There’s got to be a better way. And there is! Here’s how. This works with Fedora 20. Your mileage may vary with other distros.

1. Read this article. It will explain the basics, but follow the instructions below because there are a few differences in the process on Fedora.

2. Add the following line to /etc/NetworkManager/NetworkManager.conf under the [main] block:

   dns=dnsmasq

   This line tells NetworkManager to run a dnsmasq process.

3. Download this script that will take care of writing out a hosts style file that dnsmasq will use for name resolution.

   $ curl -o /usr/bin/virt-hosts  https://raw.github.com/awood/virt-utils/master/virt-hosts && chmod 755 /usr/bin/virt-hosts

4. $ echo "addn-hosts=/var/lib/libvirt/dnsmasq/default.addnhosts" >> /etc/NetworkManager/dnsmasq.d/virt-hosts

   This line tells NetworkManager to add the default.addnhosts file to the list of places that dnsmasq looks at for name resolution.

5. $ yum install -y incron

6. $ systemctl enable incrond.service && systemctl start incrond.service

7. Set up incron to run virt-hosts every time we detect a change in the status of a virtual machine.

   $ echo "/var/lib/libvirt/dnsmasq/default.leases IN_MODIFY /usr/bin/virt-hosts -ur" > /etc/incron.d/virt-hosts

8. Add the following line to /etc/sysconfig/network-scripts/ifcfg-em1

   DOMAIN="default.virt"

9. $ systemctl restart NetworkManager

10. $ ssh root@your-vm

Done!

¹ The arp table solution seems really simple, but half the time my VMs vanish from the arp table and I can’t get their IP anymore.